Current analyzers, as are used as a matter of routine in analytics, forensics, microbiology and clinical diagnostics, are able to carry out a multiplicity of detection reactions and analyses with a multiplicity of samples. In order to be able to carry out a multiplicity of examinations in an automated manner, various automatically operating apparatuses for the spatial transfer of measuring cells, reaction containers and reagent liquid containers are required, such as, e.g., transfer arms with a gripper function, transport belts or rotatable transport wheels, and apparatuses for transferring liquids, such as, e.g., pipetting apparatuses. The machines comprise a central control unit which, by means of appropriate software, is able to largely independently plan and work through the work steps for the desired analyses.
Many of the analysis methods used in such analyzers operating in an automated manner are based on optical methods. Measurement systems based on photometric (e.g. turbidimetric, nephelometric, fluorometric or luminometric) or radiometric measurement principles are particularly widespread. These methods enable the qualitative and quantitative detection of analytes in liquid samples without having to provide additional separation steps. The determination of clinically relevant parameters, such as, e.g., the concentration or the activity of an analyte, is often implemented by virtue of an aliquot of a bodily fluid of a patient being mixed simultaneously or in succession with one or more reagent liquids in a reaction vessel, as a result of which a biochemical reaction is put into motion, which brings about a measurable change in an optical property of the test preparation.
The measurement result is, in turn, forwarded into a memory unit by the measurement system and evaluated. Subsequently, the analyzer supplies a user with sample-specific measurement values by way of an output medium, such as, e.g., a monitor, a printer or a network connection.
For the spatial transfer of liquid containers, provision is often made of grippers for capturing, holding and releasing a liquid container, said grippers being attached to a horizontally and vertically movable transfer arm. EP-A2-2308588 describes an exemplary apparatus for transferring tube-shaped reaction vessels (cuvettes) within an automated analyzer. The apparatus comprises a passive, elastically deformable gripper for the force-fit capture and hold of a liquid container and it is suitable to receive an individual cuvette placed in a receiving position, transport said cuvette to a target position and put it down there in a further receiving position. EP-A2-2730927 describes another exemplary apparatus for transferring reagent liquid containers within an automated analyzer.
A problem is that, when transporting liquid containers, there may—during pickup, during the transport itself or else when placing down the container—be an error and the container may be lost. By way of example, a container may fall over or fall out of a transport apparatus and thus come to rest in an uncontrolled manner somewhere in the interior of the analyzer. In so doing, there may be significant contamination in the interior of the analyzer as a result of liquid spraying or flowing out of the container, particularly if this relates to unsealed liquid containers such as, e.g., reaction vessels. A particular problem is that spraying liquid may also enter other liquid containers, such as, e.g., other reaction vessels or reagent liquid containers, as result of which the liquids contained therein or to be dispensed therein are contaminated. Since the measurement of a contaminated sample or the use of a contaminated reagent may lead to erroneous measurement results, it is necessary to ensure that, firstly, the loss of a liquid container is automatically identified by the analyzer and that, secondly, a user is informed about the incident.
It is known that various sensor systems are used for identifying a loss of a liquid container, for example, Hall sensor systems at the gripper apparatuses, photoelectric barrier systems in the receiving positions for the liquid containers, or else cameras.
A known automated analyzer is configured in such a way that, if a loss of a reaction vessel is identified, it is only the measurements for reaction mixes in those reaction vessels which are already in the measurement station that are still completed, while all other planned measurements are stopped. Only once a user has ensured that there has been no contamination or that said contamination has been removed can the analyzer continue anew with working through the planned measurements.
This configuration is disadvantageous in that a timely user intervention is required for each incident in which a reaction vessel is lost, i.e., even in those incidents in which no contamination arose because, for example, an empty reaction vessel was lost, in order to lift the break in operation of the analyzer as quickly as possible. This system configuration offers a high degree of safety but requires regular attendance of a user and hence a high maintenance outlay, or causes a reduction in the overall throughput of the analyzer if a user cannot process the incident in a timely manner.